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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 577 records · Page 32Linked to original sources
PubMed1987

Characterization of EBV-carrying B-cell populations in healthy seropositive individuals with regard to density, release of transforming virus and spontaneous outgrowth.

Peripheral or tonsil lymphocyte populations of EBV-seropositive donors give rise to EBV-carrying LCLs upon in vitro explantation. Such lines can arise either by a 2-step mechanism, namely release of virus from some of the explanted cells followed by infection of previously uninfected B cells, or by direct outgrowth of virus-harboring B cells (Rickinson et al., 1974; Dalens et al., 1975; Hinuma and Katsuki 1978; Katsuki et al., 1979). We observed that cells responsible for both the 2-step mechanism and for direct outgrowth are found in the purified B-cell compartment. Virus release was more frequent than direct outgrowth. The majority of virus-releasing cells were found in the low-density fraction that contains large, activated B blasts. Cells that were capable of spontaneous outgrowth in the presence of the viral inhibitor PFA and of virus-neutralizing antibody gave rise to cell lines that carried the sex chromosome marker of the original donor, rather than that of admixed cord blood lymphocyte of the opposite sex. Such cells were found in both the low- and the high-density fractions. The majority of the EBV-carrying B cells in vivo are thus low-density blasts. Rare small B cells of high density harboring EBV were capable of spontaneous outgrowth. This may be indicative of a host control mechanism that is removed upon cultivation in vitro.

B-Lymphocytes↗
PubMed1987

EBV-transformed lymphoblastoid cell lines down-regulate EBNA in parallel with secretory differentiation.

Four monoclonal and one polyclonal lymphoblastoid cell line (LCL) were studied with regard to cytoplasmic immunoglobulin (cIg) expression, presence of the Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA) and DNA synthesis. Each line was found to consist of two subpopulations, with only minimal overlap. Proliferating, EBNA-positive, cIg-negative cells formed the majority. The minority were EBNA-negative, contained abundant cIg and were largely non-proliferating. This suggests the continuous occurrence of a maturation process within each LCL. The concomitant down-regulation of EBNA raises the interesting question whether continued synthesis of the nuclear antigen is incompatible with differentiation for epigenetic reasons, or, alternatively, whether differentiation takes place when the viral genomes are suppressed or lost.

Antigens, Viral↗
PubMed1987

Expression of B-cell-specific markers in different Burkitt lymphoma subgroups.

Forty-three Burkitt lymphoma (BL) lines were examined for the expression of 5 monoclonal antibody (MAb)-identified B-cell-specific markers and immunoglobulin production. All (13) EBV-negative BL lines were CALLA+ LB-1-, whereas 30 EBV-carrying lines showed a more heterogeneous pattern. In the EBV-negative lines, the follicle mantle zone markers BA-1 and 35.1C5 were expressed concordantly, at a different level in each line. This coordination was disrupted in EBV-carrying lines. In the EBV-negative lines, there was also an inverted correlation between the expression of 35.1C5 and the germinal center marker BLA, suggesting that some etiologically important event, perhaps the translocation, had fixed the cells at different stages of their transition from one zone to the other. This inverted relationship was also disrupted in the EBV-carrying lines, suggesting that EBV can interfere with the maturation program of the BL cell. This conclusion was also supported by a comparison between 5 EBV-negative BL lines and their EBV-converted sublines. All converted lines have undergone marker changes, but the degree and nature of these changes was different for each EBV-BL line. Both the coordinated expression of BA-1 and 35.1C5 and the inverted relationship between CALLA and LB-1 were disrupted in several other convertants. We have reexamined our previous finding (Ehlin-Henriksson and Klein, 1984) that the majority of the variant translocation-carrying BL lines were CALLA- LB-1+, in contrast to the majority of the typical translocation carriers that were mostly CALLA+ LB-1-. All II EBV-negative lines were CALLA+ LB-1-, irrespective of the type of translocation. Among the EBV-carrying lines, 4 of 17 typical (8;14) translocation carriers were CALLA- LB-1+, whereas 7 of the 12 variant translocation-carrying lines were CALLA- LB-1+. The remaining two expressed both antigens to some extent. The difference is statistically significant at the 0.03 level.

Antigens, Neoplasm↗
PubMed1987

Overall changes in chromatin sensitivity to DNase I during differentiation.

The DNase I sensitivity of total chromatin was studied in fixed cells and nuclei isolated from proliferating and terminally differentiated cells, by measuring the incorporation of labelled nucleotides into DNase-sensitive sites, and electrophoresis of DNA isolated from DNase-treated nuclei. The unfixed nuclei were sensitive to digestion at around 10 micrograms/ml, the fixed cells at 30 ng/ml DNase I concentration. Proliferating Rauscher leukemia cells were more digestible than normal spleen cells. The DNase I sensitivity of the human HL60 leukemia line decreased upon DMSO-induced differentiation but still exceeded the digestibility of nuclei from normal human peripheral blood. A novel flow-cytometric technique was developed to study DNase sensitivity at the cell level. It confirmed the relative resistance of differentiated cells to DNase I and ruled out the possibility that this could be due to an altered distribution of cell cycle phases. The overall DNase I sensitivity of chromatin was compared with the sensitivity of the c-myc gene and the myc-associated hypersensitive sites. The latter sites were detected at 1 microgram/ml DNase I in HL60 nuclei. They disappeared partially upon DMSO-induced differentiation. At 10 micrograms/ml, myc was degraded in both growing and differentiating HL60, but not in HPB cells. These data suggest that a progressive condensation of the chromatin occurs during terminal differentiation which gradually involves specific genes that need to be inactivated.

Animals↗
PubMed1987

Analysis of Epstein-Barr virus-specific and non-specific immune functions in a patient during the development of a non-Hodgkin's lymphoma.

A 57-year-old woman who presented with a reactive non-malignant lymphadenopathy was observed subsequently during the development of a nodular centroblastic non-Hodgkin's B-cell lymphoma. The Epstein-Barr virus (EBV)-specific antibody profile and EBV-specific and non-specific cell-mediated immune functions were determined at first presentation, and at various times during progression, in order to determine whether EBV was causally involved in the lymphoma and to assess in general the patient's cell-mediated immune function. At presentation, an immunodeficient status was suggested by an EBV-specific antibody profile indicative of an activated persistent infection; high antibody titers to viral capsid antigen (VCA) and early antigens (EA), but a low level of antibodies to EBV nuclear antigen (EBNA) confirmed by lack of leukocyte migration inhibition in response to EBNA (LMI-EBNA). The number of positive cells reactive with OKIa1 monoclonal antibody was significantly depressed, as was also the natural and interferon-activated killing (NK-IAK). After emergence of the lymphoma, NK-IAK reactivity and spontaneous lymphocyte DNA synthesis augmented in parallel with an increase in the frequency of Leu-7+ blood lymphocytes. The EBV-specific cell-mediated response, reflected by the outgrowth inhibition (OI) test was abolished in parallel with a decrease in the frequency of OKT3- and OKT4-positive lymphocytes.

Cell Migration Inhibition↗
PubMed1987

Esophageal perforation in the neonate: an emerging problem in the newborn nursery.

We report 11 cases of esophageal perforation in the neonate, in whom no surgery was performed for repair of the perforation, nor was any cervical or mediastinal drainage carried out. The perforation was in the cervical esophagus in all cases where an esophagram was performed. Nine were in premature babies (580 to 1,350 g), and two were full-term babies. There were two deaths in small prematures (580 and 935 g), from extreme prematurity and intraventricular hemorrhage, with no morbidity or mortality related to the esophageal perforation. The babies presented as esophageal atresia, or pneumothorax with the feeding tube in the right chest, or an abnormal right upper extrapleural air collection with infiltrate. Barium esophagram showed a classic "double esophagus" configuration. Two babies were mistakenly operated on, one with a diagnosis of esophageal duplication, and one had a gastrostomy for a diagnosis of esophageal atresia. Esophageal perforation in the neonate is an iatrogenic disease that may mimic esophageal atresia, and may be managed without surgical intervention.

Diagnosis, Differential↗
PubMed1987

Interferon gamma induces lung colonization by intravenously inoculated B16 melanoma cells in parallel with enhanced expression of class I major histocompatibility complex antigens.

Treatment of H-2-deficient nonmetastatic B16 melanoma cells with physiological doses of interferon gamma (IFN-gamma) reduced cellular growth in vitro but induced a shift to the lung-colonizing phenotype as assessed after intravenous injection of the treated cells. As little as 1 antiviral unit of recombinant IFN-gamma per ml induced B16 cells to form 3-40 pulmonary metastases in each injected mouse, whereas a 1000-fold higher concentration of IFN-beta was required to see similar effects. IFN-gamma may induce cell-surface molecules that contribute to the metastatic ability of the tumor cells. The efficient enhancement of metastatic ability after IFN-gamma treatment of the B16 cells was paralleled by an increased H-2 antigen expression and decreased sensitivity to natural killer cells. The experiments support the idea that metastasis may not depend exclusively on stable genetic changes or heterogeneity within a tumor population but may be also influenced through the modulation of the phenotype by physiological or pharmacological agents. The results are also discussed with regard to the role of different effector cells in tumor cell clearance and in relation to lymphokine-based strategies for therapy.

Animals↗
PubMed1987

Down-regulation of class I HLA antigens and of the Epstein-Barr virus-encoded latent membrane protein in Burkitt lymphoma lines.

Epstein-Barr virus (EBV)-carrying Burkitt lymphoma (BL) cells are relatively or completely resistant to the lytic effect of major histocompatibility complex class I HLA antigen-restricted cytotoxic T lymphocytes (CTLs) generated by stimulating lymphocytes of EBV-seropositive donors with the autologous EBV-transformed lymphoblastoid cell line (LCL). We previously found that EBV-negative and EBV-carrying BL lines derived from HLA-A11-positive donors were not only resistant to lysis by the HLA-A11-restricted CTL generated by stimulation with the autologous LCL, but also to HLA-A11-specific CTL derived from lymphocytes of an EBV-seronegative donor stimulated with an allogeneic LCL. Using the same and additional cell lines, we now show that the CTL resistance of the BL lines is probably due to a selective down-regulation of HLA-A11. We also show that the EBV-encoded latent membrane protein is expressed at a lower level in the EBV-carrying BL lines than in EBV-transformed LCLs. Only one of eight in vitro EBV-converted BL lines that shifted to a more LCL-like growth pattern expressed LMP at a high level. This line also reexpressed the HLA-A11 antigen that was undetectable in its EBV-negative progenitor. Our findings suggest that the typical BL cell phenotype is associated with low expression of both proteins.

Antigens, Neoplasm↗
PubMed1987

Antibody responses to Epstein-Barr virus-determined nuclear antigen (EBNA)-1 and EBNA-2 in acute and chronic Epstein-Barr virus infection.

Five distinct Epstein-Barr virus (EBV)-determined nuclear antigens (EBNA-1 to EBNA-5) were recently identified. Antibody responses to these antigens could conceivably differ, and thus prove of serodiagnostic value, in EBV-associated disease processes. As a first step, murine or human cell lines transfected with appropriate EBV DNA fragments and stably expressing either EBNA-1 or EBNA-2 were used to determine the frequency and time of emergence of antibodies to these two antigens in the course of acute and chronic infectious mononucleosis (IM) and to assess their titers in so-called chronic active EBV infections. Following IM, antibodies to EBNA-2 arose first and, after reaching peak titers, declined again in time to lower persistent or even nondetectable levels. Antibodies to EBNA-1 emerged several weeks or months after anti-EBNA-2 and gradually attained the titers at which they persisted indefinitely. The ratios between the anti-EBNA-1 and anti-EBNA-2 titers therefore were generally well below 1.0 during the first 6-12 months after IM and turned to well above 1.0 during the second year. In clear cases of chronic IM, the inversion of this ratio was delayed or prevented. In the less well-defined chronic EBV infections, low ratios were observed in only some of the patients. Because many of these illnesses were not ushered in by a proven IM and often showed EBV-specific antibody profiles within the normally expected range, a causal role of the virus in these cases remains doubtful.

Acute Disease↗
PubMed1987

Nuclear DNA-binding proteins determined by the Epstein-Barr virus-related simian lymphotropic herpesviruses H. gorilla, H. pan, H. pongo and H. papio.

Nuclear DNA-binding proteins were extracted from lymphoblastoid cell lines transformed with Epstein-Barr virus (EBV) or with the related lymphotropic herpesviruses of gorilla (Herpesvirus gorilla), chimpanzee (H. pan), baboon (H. papio) or orang-utan (H. pongo). They were immunoblotted with the sera of all four simian species in comparison with EBV antibody-positive human sera. Eight nuclear proteins were identified, and were designated GONA-1 and GONA-2 for H. gorilla-determined nuclear antigens, PANA-1A, PANA-1B and PANA-2 for H. pan, PONA-2 for H. pongo and HUPNA-1 and HUPNA-2 for H. papio-determined nuclear antigens. One of two tested HUPNA-2-positive baboon sera and one PONA-2-positive orang-utan serum also reacted with EBNA-2 in EBV-transformed cells. A human serum that contained antibodies to all five EBNA proteins cross-reacted only with PANA-2 and PONA-2. Monospecific anti-peptide antibodies against EBNA-2, type A, also reacted with PONA-2, but not with the other simian nuclear antigens. The data provide evidence that EBV-like simian lymphotropic herpesviruses induce EBNA-like nuclear antigens and that EBNA-2 and some simian EBNA-related proteins contain an epitope that has been conserved during the evolution of the EBV family of viruses.

Animals↗
PubMed1987

Monoclonal and polyclonal antibodies against Epstein-Barr virus nuclear antigen 5 (EBNA-5) detect multiple protein species in Burkitt's lymphoma and lymphoblastoid cell lines.

The Epstein-Barr virus nuclear antigen 5 (EBNA-5) is encoded by highly spliced mRNA from the major IR1 (BamHI-W) repeat region of the virus genome. A mouse monoclonal antibody, JF186, has been raised against a synthetic 18-amino-acid peptide deduced from the EBNA-5 message of B95-8 and Raji cells. The antibody showed characteristic coarse nuclear granules by indirect immunofluorescence and revealed multiple EBNA-5 species by immunoblotting and immunoprecipitation. The B95-8 line itself and all B95-8 virus-carrying cells, whether lymphoblastoid cell lines or in vitro-converted sublines of Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL) lines, were EBNA-5 positive. Among 36 cell lines carrying different EBV strains, only 10 expressed the B95-8-Raji-prototype EBNA-5 recognized by JF186; this was probably due to genetic variation in the epitope recognized by JF186, as shown for P3HR-1. Human antibodies, affinity purified against EBNA-5-JF186 immunoprecipitates, detected EBNA-5 in the majority of EBV-positive BL lines and in all lymphoblastoid cell lines containing the BL-derived viruses. Thus, EBNA-5 can be expressed by all virus isolates examined, but is down-regulated, together with other latent gene products, in a minority of BL lines which have a particular cellular phenotype. EBNA-5 was detected as a ladder of protein species of 20 to 130 kilodaltons (kDa), with a regular spacing of 6 to 8 kDa, consistent with the coding capacity of the combined BamHI-W 66- and 132-base-pair exons, together with shifts of 2 to 4 kDa, consistent with the size of the separate 66- and 132-base-pair exons. Multiple EBNA-5 proteins can be expressed by the single cell as shown by cloning of newly infected cells.

Animals↗
PubMed1987

Molecular characterization of novel reciprocal translocation t(6;14) in an Epstein-Barr virus-transformed B cell precursor.

An in vitro culture of FLEB14 cells, an Epstein-Barr virus-transformed B cell precursor containing the germ line immunoglobulin genes, gave rise to a uniclonally expanded variant, FLEB14 delta 3, which was rearranged at the immunoglobulin heavy-chain gene locus. Cytogenetic analysis showed that FLEB14 delta 3 had a novel reciprocal translocation, t(6;14)(q15;q32). Molecular cloning of the rearranged DNA fragments and determination of their nucleotide sequence revealed that the recombination event was reciprocal, imprecise, and nonhomologous and took place in the S mu region, like those found in Burkitt's lymphoma cells. We propose a molecular model to explain this genetic event which may be relevant to class switch recombination. The translocated sequence of chromosome 6 did not contain any known oncogenes, although the sequence is conserved among mammals. FLEB14 delta 3 did not show tumorigenicity.

B-Lymphocytes↗
PubMed1987

The rat MIS1/Pvt-1 locus is syntenic with MYC on chromosome 7.

Mouse Pvt-1 and rat MIS1 are frequent proviral integration sites in retrovirally induced lymphomas. The Pvt-1 locus is also involved in mouse plasmacytoma (6;15) and in the variant Burkitt lymphoma (2;8) translocations. We show that the Pvt-1/MIS1 locus is syntenic with MYC on rat chromosome 7. This is consistent with a postulate of close linkage and, possibly, a functional relationship between the MYC protooncogene and the MIS1/Pvt-1 locus.

Animals↗
PubMed1987

[Spontaneous variability of ventricular extrasystoles: criteria for validating anti-arrhythmia therapy in relation to the length of the control interval].

Calculations about the variability of PVCs are usually based upon the results of two Holter ECGs, either successive ones or separated by a short interval. No studies are available indicating whether the criteria calculated for short control intervals also holds true when evaluating chronic antiarrhythmic treatment over longer control periods. This study was performed to investigate the influence of the length of the control interval on the spontaneous variability and thus on the reduction of PVCs required to secure an antiarrhythmic effect. In a prospective study, 444 ambulatory ECGs were obtained in 90 patients with CAD or IDC and untreated ventricular arrhythmia of Lown grade IV. Patient follow-up was carried out over an average of 181 +/- 297 days. The degree of arrhythmia was expressed as the mean hourly PVC rate. The variability of PVC counts between two Holter ECGs was defined as the logarithm of the quotient PVCday 2(n + 1)/PVCday 1(n + 1). The spontaneous distribution of variability quotients was defined separately (mean +/- 2 SD) for each of four ranges of control intervals (0-6 days, 7-89 days, 90-364 days, greater than or equal to 365 days). The per cent reduction (R) in PVC frequency necessary to establish drug efficacy, was calculated according to the formula R (%) = 10(0)-10(-2SD) X 100, whereas the percentage change necessary to prove aggravation of arrhythmia (A) was assessed by the formula A (%) = 10(0)+10(+2SD X 100. R increased from 63% (0-6 days), 81% (7-89 days), 93% (90-364 days) to 98% (greater than or equal to 365 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1987

[Diagnosis of pulmonary hypertension using pulsed Doppler cardiography].

The accuracy of pulsed Doppler cardiography in predicting pulmonary hypertension was assessed in 70 patients (aged 16-72 years) with varying cardiac disease, who had undergone catheterization. Doppler velocity traces were recorded from four sampling sites in the pulmonary outflow tract and from the tricuspid valve. These results were compared to the invasive data. An inverse correlation (r = -0.77) was found between acceleration time (onset of RV ejection to peak pulmonary velocity) and mean pulmonary arterial pressure, with the sampling site in the centre of the pulmonary valves or of the RV outflow tract (r = -0.71). Acceleration time was inversely related to patient age but was not dependent on heart rate or on cardiac output. The sensitivity of the acceleration time was 85-91% for the diagnosis of moderate or severe pulmonary hypertension, and the predictive value was greater than 90%. The following measurements were less helpful in diagnosing pulmonary hypertension: peak velocity of pulmonary arterial blood flow, its mean acceleration, RV isovolumic relaxation time and the qualitative sign of a presystolic pulmonary flow wave induced by atrial contraction. A reversal of systolic flow at the level of the pulmonic valves, measured as time of forward flow in percent of RV ejection time, was found only in patients with moderate or severe pulmonary hypertension. This was a sensitive marker of an elevated pulmonary arterial resistance (greater than or equal to 95%), the mechanism of which is not yet fully understood.

Adolescent↗